1. Field of the Invention
This invention relates to a device for degrading those fuels, commonly referred to as safety fuels, which include an anti-mist additive of a high molecular weight polymer, and in particular for devices for degrading anti-mist kerosene (AMK). Such fuels have been developed for use in aircraft but will not readily pass through the filters or other small orifices which form part of a fuel metering system for an aircraft engine. Thus, it is necessary to reduce the molecular weight of the polymer in the fuel before supplying it to a metering system. This process is generally referred to as degrading the fuel.
2. Brief Description of the Prior Art
UK Patent Specification No. 1,259,113 indicates that when AMK reaches a location in a fuel system where the risk of its dissemination as a mist is no longer a hazard, the molecules of the polymer additive may readily be reduced in molecular weight by a suitable degradation process, for example by mechanical shearing. It has now been discovered that degradation can be effected by subjecting the AMK to various mechanical forces, tensile forces being at least as effective as shear forces. Aircraft fuel systems moreover commonly include a first stage, lower pressure pump, by means of which fuel is delivered to a second stage, high pressure pump.